There is no clear prohibition about oral sex in the Qur'an
or the sunnah of the Prophet (SAAWS). However, according to many
jurists, the fluids that the male of female organs emit during
the time of sexual excitement, such as many (sperm) or madhi;
etc., are all considered negis and they should not touch the
mouth of the man or the woman. It is for this reason that many
scholars do not recommend this practice and consider it makrooh.